Marine Ecology Research CentreCopyright (c) 2016 Southern Cross University All rights reserved.http://epubs.scu.edu.au/merc_pubs
Recent documents in Marine Ecology Research Centreen-usThu, 20 Oct 2016 01:57:12 PDT3600Is the Antarctic Ophryotrocha orensanzi (Annelida: Dorvilleidae) a circumpolar non-specialized opportunist?http://epubs.scu.edu.au/merc_pubs/85
http://epubs.scu.edu.au/merc_pubs/85Tue, 18 Oct 2016 20:28:26 PDT
The dorvilleid polychaete Ophryotrocha orensanzi is reported from the vicinity of Casey station, East Antarctica, an astounding range extension from its previous records in the South Shetland Islands to the opposite side of the Antarctic continent, suggesting that it is a circumpolar species. Genetic studies confirmed the conspecificity and the inferred haplotype network suggests that the two populations studied are genetically connected. Morphological studies of the newly collected material revealed that the jaw apparatus consists of the P- and K-type, in accordance with other members of the ‘lobifera’ clade. We are reporting a previously undocumented button-like structure that we are referring to as ‘nuchal papilla’ for its association with the nuchal region, and present an emended diagnosis for the species. The Casey station population was collected in a clean, unpolluted intertidal environment associated with stones and seaweeds. We are challenging the generally held opinion that Ophryotrochaspecies are specialists of organically enriched substrates, suggesting that, at least for the particulars ofO. orensanzi, they might also be unspecialized opportunists, able to exist in the most pristine environments and having the ability to rapidly increase their population sizes under favourable conditions.
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Hannelore Paxton et al.Diverse associations among coral host haplotypes and algal endosymbionts may drive adaptation at geographically peripheral and ecologically marginal locationshttp://epubs.scu.edu.au/merc_pubs/84
http://epubs.scu.edu.au/merc_pubs/84Wed, 20 Apr 2016 22:45:08 PDTAnnika ME Noreen et al.Tropical Atlantic temperature seasonality at the end of the last interglacialhttp://epubs.scu.edu.au/merc_pubs/83
http://epubs.scu.edu.au/merc_pubs/83Wed, 20 Apr 2016 19:03:38 PDT
The end of the last interglacial period, ~118 kyr ago, was characterized by substantial ocean circulation and climate perturbations resulting from instabilities of polar ice sheets. These perturbations are crucial for a better understanding of future climate change. The seasonal temperature changes of the tropical ocean, however, which play an important role in seasonal climate extremes such as hurricanes, floods and droughts at the present day, are not well known for this period that led into the last glacial. Here we present a monthly resolved snapshot of reconstructed sea surface temperature in the tropical North Atlantic Ocean for 117.7±0.8 kyr ago, using coral Sr/Ca and δ18O records. We find that temperature seasonality was similar to today, which is consistent with the orbital insolation forcing. Our coral and climate model results suggest that temperature seasonality of the tropical surface ocean is controlled mainly by orbital insolation changes during interglacials.
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Thomas Felis et al.Biochar from commercially cultivated seaweed for soil ameliorationhttp://epubs.scu.edu.au/merc_pubs/82
http://epubs.scu.edu.au/merc_pubs/82Tue, 19 Apr 2016 19:35:28 PDT
Seaweed cultivation is a high growth industry that is primarily targeted at human food and hydrocolloid markets. However, seaweed biomass also offers a feedstock for the production of nutrient-rich biochar for soil amelioration. We provide the first data of biochar yield and characteristics from intensively cultivated seaweeds (Saccharina, Undaria and Sargassum – brown seaweeds, and Gracilaria, Kappaphycus and Eucheuma – red seaweeds). While there is some variability in biochar properties as a function of the origin of seaweed, there are several defining and consistent characteristics of seaweed biochar, in particular a relatively low C content and surface area but high yield, essential trace elements (N, P and K) and exchangeable cations (particularly K). The pH of seaweed biochar ranges from neutral (7) to alkaline (11), allowing for broad-spectrum applications in diverse soil types. We find that seaweed biochar is a unique material for soil amelioration that is consistently different to biochar derived from ligno-cellulosic feedstock. Blending of seaweed and ligno-cellulosic biochar could provide a soil ameliorant that combines a high fixed C content with a mineral-rich substrate to enhance crop productivity.
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David A. Roberts et al.Comparison of several different neutralisations to a bauxite refinery residue: potential effectiveness environmental ameliorantshttp://epubs.scu.edu.au/merc_pubs/81
http://epubs.scu.edu.au/merc_pubs/81Tue, 19 Apr 2016 18:32:46 PDT
Bauxite refinery residues (BRR) remain the single largest environmental problem for the alumina industry, because of the fine-grained nature (>90% at <10 >μm), high pH (>13), high sodicity (>50 g/kg), and high alkalinity (typically ≈30 g/kg as equivalent CaCO3). However, neutralisation of BRR provides a geochemically engineered solution, with potential re-use options. Hence, we compare the geochemistry of 4 BRRs: the un-neutralised raw red mud (UNRM), a CO2-neutralised red mud (CNRM), a Basecon™-neutralised (Basecon™) red mud, and a CO2-neutralisation followed by a Basecon™-neutralisation (Hybrid) material from a common source for reuse potential. Compositional changes, including acid neutralising capacity, trace-metal and phosphorous binding capacities, and toxicity leaching characteristics (TCLP) show that different neutralisations produce two geochemically distinct solids, those without alkalinity precipitation, and those with solid alkalinity. From the work completed, both Basecon™-neutralised and Hybrid materials have a significantly higher reuse potential for environmental remediation programs, such as acid rock drainage neutralisations, wastewater treatment, and/or artificial soil construction.
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Malcolm W. Clark et al.Echinoderms piggybacking on sea cucumbers: benign effects on sediment turnover and movement of hostshttp://epubs.scu.edu.au/merc_pubs/79
http://epubs.scu.edu.au/merc_pubs/79Sun, 24 May 2015 20:29:41 PDT
Sea cucumbers (Holothuroidea) are known to host ectocommensal animals but echinoderm epibionts have never been reported nor their effects on hosts appraised quantitatively. At one location in New Caledonia, we found a high number of ophiuroids (Ophiothela cf. danae) and synaptid sea cucumbers (Synaptula media and Synaptula sp.) living on the bumpy external body wall of sea cucumbers, Stichopus herrmanni. Rates of midday sediment defecation (mean: 23 g h−1) and short-term displacements (mean: 60 cm h−1) by the hosts were not significantly affected by the number of echinoderm commensals they carried. The frequent relationships at the location suggest that such facultative commensalism between echinoderms could be more common than previously understood. Appreciable numbers of scaleworms, crabs and shrimps on the sea cucumbers show that sea cucumbers can act as hosts to echinoderms and other epibiotic taxa, bolstering the notion that they play important ecological roles in reef ecosystems.
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Steven W. Purcell et al.Critical Thermal Minima of age-0 Australian bass, Macquaria novemaculeata, fingerlings: implications for stocking programmeshttp://epubs.scu.edu.au/merc_pubs/78
http://epubs.scu.edu.au/merc_pubs/78Wed, 10 Apr 2013 17:52:20 PDT
Fishes are often stocked outside natural distribution ranges with inadequate information on target streams, particularly thermal regimes. Australian bass, Macquaria novemaculeata (Steindachner), is a catadromous species that is regularly stocked into upland reaches of rivers and impoundments in south-eastern Australia. Critical Thermal Minima (CTMin) were determined for age-0 Australian bass fingerlings with a mean fork length of 64.4 ± 0.4 mm and weighing 3.8 ± 0.8 g. Four treatments were used, including three replicate aquaria for each treatment. Fingerlings were acclimated at either 8 or 15 °C at densities of 15 fish in 56-L glass aquaria. Water temperatures were then decreased at either 1 °C day−1 or 1 °C h−1 until loss of equilibrium (LOE), which occurred between 3 and 7 °C. Mean CTMin among treatments was 3.22–4.64 °C and was influenced by acclimation temperature and rate of temperature decline. Fingerlings acclimated at 8 °C subjected to a temperature decline of 1 °C h−1 experienced highest LOE temperature. Post-LOE mortality among treatments was highest at 100% in the 8 °C acclimation with a 1 °C day−1 temperature decline. Mortalities following LOE occurred within 5 days. The results suggest that stocking age-0 Australian bass is unlikely to be successful in areas where winter temperatures fall below 6 °C.
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Cameron M. Leo et al.Influence of elevated temperatures on the antiviral and antibacterial immune response of abalone, Haliotis rubrahttp://epubs.scu.edu.au/merc_pubs/77
http://epubs.scu.edu.au/merc_pubs/77Thu, 21 Mar 2013 22:02:59 PDT
Elevated water temperature can act as a stressor impacting the immune responses of molluscs, potentially increasing their susceptibility to microbial infections. Abalone are commercially important marine molluscs that have recently experienced disease outbreaks caused by a herpesvirus and Vibrio bacteria. Sampling of wild-caught Haliotis rubra showed a significant correlation between water temperature and both antiviral and antibacterial activity, with higher activity in summer than in winter months. However, antibacterial activity was compromised in favour of antiviral activity as the water temperatures peaked in summer. A controlled laboratory experiment was then used to investigate several immune responses of H. rubra, including total haemocyte count (THC), stimulated superoxide anion production (SO), antiviral activity against a model herpesvirus, herpes simplex virus type 1 and antibacterial activity against a representative pathogenic bacterium, Vibrio anguillarum, over one week after raising water temperature from 18 to 21 or 24 °C. THC and SO increased at day 1 and then dropped back to control levels by days 3 and 7. By comparison, the humoural immune parameters showed a delayed response with antibacterial and antiviral activity significantly increasing on days 3 and 7, respectively. Consistent with the field study, antibacterial activity became significantly depressed after prolonged exposure to elevated temperatures. A principal components analysis on the combined immune parameters showed a negative correlation between antiviral and antibacterial activity. SO was positively correlated to THC and neither of these cellular parameters were correlated to the humoural antimicrobial activity. Overall, this study indicates that abalone may have more resilience to viruses than bacterial pathogens under conditions of elevated temperature, such as those predicted under future climate change scenarios.
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Vinh T. Dang et al.Effects of reef proximity on the structure of fish assemblages of unconsolidated substratahttp://epubs.scu.edu.au/merc_pubs/76
http://epubs.scu.edu.au/merc_pubs/76Tue, 19 Mar 2013 14:29:56 PDT
Fish assemblages of unconsolidated sedimentary habitats on continental shelves are poorly described when compared to those of hard substrata. This lack of data restricts the objective management of these extensive benthic habitats. In the context of protecting representative areas of all community types, one important question is the nature of the transition from reefal to sedimentary fish assemblages. We addressed this question using Baited Remote Underwater Videos (BRUVs) to assess fish assemblages of sedimentary habitats at six distances from rocky reefs (0, 25, 50, 100, 200, and 400 m) at four sites in subtropical eastern Australia. Distance from reef was important in determining fish assemblage structure, and there was no overlap between reef sites and sedimentary sites 400 m from reef. While there was a gradient in assemblage structure at intermediate distances, this was not consistent across sites. All sites, however, supported a mixed ‘halo’ assemblage comprising both reef and sediment species at sampling stations close to reef. BRUVs used in conjunction with high-resolution bathymetric and backscatter spatial data can resolve differences in assemblage structure at small spatial scales (10s to 100s of metres), and has further application in unconsolidated habitats. Unless a ‘reef halo’ assemblage is being examined, a minimum of 200 m but preferably 400 m distance from any hard substrate is recommended when designing broader-scale assessments of fish assemblages of sedimentary habitats.
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Arthur L. Schultz et al.Shipworms as a model for competition and coexistence in specialized habitatshttp://epubs.scu.edu.au/merc_pubs/75
http://epubs.scu.edu.au/merc_pubs/75Sun, 17 Mar 2013 22:35:07 PDT
Shipworms, a group of marine wood borers (Mollusca: Teredinidae), are a model group with which to examine metacommunities inhabiting patchy, ephemeral habitats. Multiple species and genera typically share and compete for the same discrete substrata, allowing for direct comparisons to be made between competitive strategies, without confounding by extraneous biological differences. Timber recruitment panels were used to quantify 2, 4, 6 and 12 mo abundances of tropical Australian shipworm species, recording 62075 individuals from 6 genera and 19 species. Species exhibit differing peak recruitment seasons and reproductive modes, with free-spawning, short-term brooding and long-term brooding occurring. However, despite a higher diversity of spawning species (58%) overall, abundance was strongly driven by the lower diversity of short-term brooding species (37%), comprising 95.7% of recruitment. Competition for habitat was high, with up to 1200 individuals per panel (~3 ind. cm–3), and widespread (40 to 90%) mortality in panels over 4 mo old. Results show that reproductive mode is a key contributor to recruitment success, with the constraints of a patchy, ephemeral habitat favoring a ‘middle of the road’ strategy of short duration larval brooding, most effectively balancing fecundity, larval retention, and dispersive ability.
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Hugh MacIntosh et al.Crustose coralline algae and a cnidarian neuropeptide trigger larval settlement in two coral reef spongeshttp://epubs.scu.edu.au/merc_pubs/74
http://epubs.scu.edu.au/merc_pubs/74Sun, 17 Mar 2013 22:20:02 PDT
In sessile marine invertebrates, larval settlement is fundamental to population maintenance and persistence. Cues contributing to the settlement choices and metamorphosis of larvae have important implications for the success of individuals and populations, but cues mediating larval settlement for many marine invertebrates are largely unknown. This study assessed larval settlement in two common Great Barrier Reef sponges, Coscinoderma matthewsi and Rhopaloeides odorabile, to cues that enhance settlement and metamorphosis in various species of scleractinian coral larvae. Methanol extracts of the crustose coralline algae (CCA), Porolithon onkodes, corresponding to a range of concentrations, were used to determine the settlement responses of sponge larvae. Cnidarian neuropeptides (GLW-amide neuropeptides) were also tested as a settlement cue. Settlement in both sponge species was approximately two-fold higher in response to live chips of CCA and optimum concentrations of CCA extract compared to 0.2 µm filtered sea water controls. Metamorphosis also increased when larvae were exposed to GLW-amide neuropeptides; R. odorabile mean metamorphosis reached 42.0±5.8% compared to 16.0±2.4% in seawater controls and in C. matthewsi mean metamorphosis reached 68.3±5.4% compared to 36.7±3.3% in seawater controls. These results demonstrate the contributing role chemosensory communication plays in the ability of sponge larvae to identify suitable habitat for successful recruitment. It also raises the possibility that larvae from distinct phyla may share signal transduction pathways involved in metamorphosis.
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Steve W. Whalan et al.Thermal and sedimentation stress are unlikely causes of brown spot syndrome in the coral reef sponge, Ianthella bastahttp://epubs.scu.edu.au/merc_pubs/73
http://epubs.scu.edu.au/merc_pubs/73Sun, 17 Mar 2013 22:12:25 PDT

Background

Marine diseases are being increasingly linked to anthropogenic factors including global and local stressors. On the Great Barrier Reef, up to 66% of the Ianthella basta population was recently found to be afflicted by a syndrome characterized by brown spot lesions and necrotic tissue.

Methodology/Principal Findings

Manipulative experiments were undertaken to ascertain the role of environmental stressors in this syndrome. Specifically, the effects of elevated temperature and sedimentation on sponge health and symbiont stability in I. basta were examined. Neither elevated temperature nor increased sedimentation were responsible for the brown spot lesions, but sponges exposed to 32°C developed substantial discoloration and deterioration of their tissues, resulting in death after eight days and a higher microbial diversity in those samples. No shifts in the microbial community of I. basta were observed across a latitudinal gradient or with increased sedimentation, with three previously described symbionts dominating the community of all sponges (Alphaproteobacteria, Gammaproteobacteria and Thaumarchaea).

Conclusions/Significance

Results from this study highlight the stable microbial community of I. basta and indicate that thermal and sedimentation stress are not responsible for the brown spot lesions currently affecting this abundant and ecologically important sponge species.

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Heidi M. Luter et al.Marine debris: a proximate threat to marine sustainability in Bootless Bay, Papua New Guineahttp://epubs.scu.edu.au/merc_pubs/72
http://epubs.scu.edu.au/merc_pubs/72Thu, 07 Mar 2013 20:22:52 PST
Surveys of stranded marine debris around Motupore Island, a small island in Bootless Bay, Papua New Guinea, revealed exceptionally high loads (up to 78.3 items m−2), with major concentrations in mangrove-dominated, depositional areas. The worst affected, 50-m stretch of shore was estimated to contain >37.000 items with a combined weight of 889 kg. Consistent with studies elsewhere, plastics comprised by far the majority of debris across all sites (89.7%). The lack of centralised waste collection and limited village-based resources, coupled with an increasing population, suggests that this issue is a long way from solution. High debris loads thwart attempts to rehabilitate depleted mangrove forests through smothering of seedlings, perpetuating run-off and water quality issues in the bay. Addressing marine debris is thus of fundamental importance for the sustainability of Bootless Bay and its resources, and a critical step in promoting ecosystem resilience.
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Stephen DA SmithSelecting zones in a marine park: early systematic planning improves cost-efficiency; combining habitat and biotic data improves effectivenesshttp://epubs.scu.edu.au/merc_pubs/71
http://epubs.scu.edu.au/merc_pubs/71Thu, 07 Mar 2013 20:02:27 PST
Systematic planning, using algorithm tools, can improve biodiversity representation in ‘no-take’ zones in a marine park while reducing costs of meeting conservation targets. The current zoning plan for the 870 km2 Solitary Islands Marine Park (SIMP), designed without algorithm tools, provides an example to compare the efficiency of zoning scenarios that include or ignore the existing zoning scheme and to assess the utility of habitat and/or biotic data for planning. Marxan was used to compare representation of habitat categories and a selection of fish species using 3 scenarios for ‘no-take’ sanctuary zones: 1) clean slate; 2) building on the existing sanctuary zones; and 3) current sanctuary zones (2002 zone plan). Three target levels were considered (10%, 20% and 30% representation of habitats and fish species in sanctuary zones). The use of habitat and fish data combined was compared with results obtained using each dataset separately. The clean-slate option was the most cost-efficient. Extending the existing sanctuary zones to achieve equivalent representation required more area and longer boundaries. For both of these scenarios, a large cross-shelf sanctuary zone at the widest part of SIMP was an important requirement for achieving representation. Neither habitat categories nor reef fish assemblages were fully represented in the current zoning plan. Fish and habitat features combined were more effective than habitat alone at selecting areas known to have high conservation values in the SIMP. The fish data in isolation were too spatially constrained for systematic planning at this scale.
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H A. Malcom et al.Cross-shelf variation in the structure of molluscan assemblages on shallow, rocky reefs in subtropical, eastern Australiahttp://epubs.scu.edu.au/merc_pubs/70
http://epubs.scu.edu.au/merc_pubs/70Thu, 07 Mar 2013 19:47:55 PST
Despite the fact that molluscs are one of the most widespread and conspicuous of all marine invertebrates, comparatively little is known about their ecology, especially with respect to biological interactions that drive community processes. We consequently assessed patterns of subtidal mollusc assemblages on subtropical rocky reefs in the Solitary Islands Marine Park (SIMP), eastern Australia. Shelled molluscs (specifically shelled gastropods and bivalves) were targeted to test if: (1) mollusc assemblages change with increasing distance from shore; (2) reef orientation (vertical and horizontal reef faces) influences assemblage structure; (3) sessile benthic communities influence the composition of mollusc assemblages. Multivariate analyses of community patterns indicated strong cross-shelf patterns. However, no significant differences were found for summary community variables (species richness, total abundance). Inshore sites were dominated by large herbivores (especially turbinids) and prey-specific ranellids. Mid-shelf assemblages comprised a mix of taxa that occurred in both inshore and offshore assemblages and were thus transitional between these shelf positions. Offshore assemblages were distinctly different to reefs closer to shore and were characterised primarily by the presence of sedentary (Vermetidae and Chamidae), and tropically-affiliated taxa. Relationships with reef orientations were found to be inconsistent and correlations with sessile benthos were relatively weak. The overall patterns are similar to those found for corals and fish in the region and most likely reflect the increasing influence of the East Australian Current offshore.
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Matthew A. Harrison et al.Abundance and diversity of anemonefishes and their host sea anemones at two mesophotic sites on the Great Barrier Reef, Australiahttp://epubs.scu.edu.au/merc_pubs/69
http://epubs.scu.edu.au/merc_pubs/69Thu, 31 Jan 2013 20:30:51 PST
Anemonefishes and their host sea anemones are iconic inhabitants of coral reef ecosystems. While studies have documented their abundance in shallow-water reef habitats in parts of the Indo-Pacific, none have examined these species on mesophotic reefs. In this study, we used autonomous underwater vehicle imagery to examine the abundance and diversity of anemones and anemonefishes at Viper Reef and Hydrographers Passage in the central Great Barrier Reef at depths between 50 and 65 m. A total of 37 host sea anemones (31 Entacmaea quadricolor and 6 Heteractis crispa) and 24 anemonefishes (23 Amphiprion akindynos and 1 A. perideraion) were observed. Densities were highest at Viper Reef, with 8.48 E. quadricolor and A. akindynos per 100 m2 of reef substratum. These results support the hypothesis that mesophotic reefs have many species common to shallow-water coral reefs and that many
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Thomas Bridge et al.Effects of micro and macroalgal diet supplementations on growth and immunity of greenlip abalone, Haliotis laevigatahttp://epubs.scu.edu.au/merc_pubs/68
http://epubs.scu.edu.au/merc_pubs/68Thu, 11 Oct 2012 00:18:12 PDT
Algae contain nutrients and bioactive compounds, which can have effects on the growth and immunity of aquatic organisms. This study examines the effect of macroalgae Ulva lactuca and Spyridia filamentosa, cyanobacteria Arthrospira maxima, and microalgae Dunaliella salina on the growth and immunity of Haliotis laevigata, in comparison to a commercially formulated pellet. Over 12 weeks, U. lactuca or S. filamentosa produced the lowest growth rate, indicating lack of nutrients for abalone growth in a single macroalgae diet. Pellets supplemented with 10% A. maxima or D. salina resulted in increased abalone shell length (13.3 and 30.7%, respectively) and body weight (19.9 and 33.4%) over the pellet control diet. The impact of algal supplementation on hemolymph immunity was mainly represented by a drop in total hemocyte counts (THC) and some diet specific effects on superoxide anion and antibacterial activity against Vibrio anguillarum. No effect of diet was observed on phagocytosis, phenoloxidase, or antiviral activity against herpes simplex virus type 1. It is conceived that the humoral antimicrobial factors in abalone hemolymph are innately biosynthesized rather than dietary derived compounds. Nevertheless, concomitant with strong antiviral activity against HSV-1 in a lipophilic extract of U. lactuca and S. filamentosa, higher antiviral activity was detected in the digestive lipid extract of abalone fed U. lactuca (64.2% at 650 μg ml−1) or S. filamentosa (69.51%) compared to abalone fed pellets (47.42%) or pellets supplemented with A. maxima (46.3%) or D. salina (46%). This suggests that abalone may also derive some protection against oral pathogens by algal derived bioactive compounds. These results indicate that abalone growth rate could be optimized by A. maxima and D. salina supplementations, whereas U. lactuca and S. filamentosa could be useful supplements for abalone aquaculture, especially in areas with high risk of herpesvirus infection.
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Vinh T. Dang et al.Habitat associated differences in temperate sponge assemblages: the importance of chemical defencehttp://epubs.scu.edu.au/merc_pubs/67
http://epubs.scu.edu.au/merc_pubs/67Tue, 26 Jun 2012 16:45:39 PDT
Sponges are important members of marine benthic communities, but, in general, little is known about the factors that influence their distribution and abundance. Here we investigated the importance of chemical defence in sponge assemblages from two adjacent shallow subtidal habitats in temperate south-eastern Australia; kelp (Ecklonia radiata) forests and urchin dominated barrens (barrens). Surveys at two sites revealed a disjunct pattern of distribution for sponges between habitats, with ten species of sponge recorded in each habitat, but none occurring in both habitats. The cover of sponge beneath the Ecklonia forest (12.7%) was significantly higher than the cover of sponge in the barrens (2%). Furthermore, sponge assemblages beneath Ecklonia forests consisted of high densities of small colonies, whereas in the barrens, relatively large colonies in low densities predominated. Crude extract of the most abundant encrusting sponges from each habitat was incorporated into an artificial diet and fed to the sea urchin Centrostephanus rodgersii at 50% and/or natural concentrations. Extract of three species of encrusting sponge from the barrens (Chondrilla australiensis, Clathria sp.1 and Darwinella australiensis) significantly deterred feeding by C. rodgersii at 50% of their natural concentration. Extract of a fourth barrens species, Pronax sp.1, did not significantly deter feeding at 50% or natural concentration. Feeding by C. rodgersii was similarly not deterred by extracts of four sponge species from the Ecklonia forests at 50% or natural concentrations. Levels of inorganic material in sponges from the two habitats were also investigated. In general, encrusting species of sponge from the barrens had very low percentages (by weight) of inorganic material in their tissue, whereas encrusting sponge species from the Ecklonia forests had very high percentages of inorganic material, ranging from 83% to 93%. This study represents the first experimental test of the effect of sponge extracts on feeding by sea urchins. It reveals differences in sponges from the two habitats and demonstrates an important anti-feedant role for extracts of encrusting sponges from the barrens habitat.
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Jeffrey T. Wright et al.The impact of diet on the growth and proximate composition of juvenile whelks, Dicathais orbita (Gastropoda : Mollusca)http://epubs.scu.edu.au/merc_pubs/66
http://epubs.scu.edu.au/merc_pubs/66Tue, 26 Jun 2012 16:45:35 PDTDicathais orbita is a predatory marine whelk of interest as a new source of protein for potential production in aquaculture. Establishment of a successful aquaculture industry based on this species will require optimisation of their diet for fast growth and survival, whilst maintaining a good proximate composition in the flesh. Here we compare the effects of four diets fed to juvenile D. orbita over a 12 week period, to evaluate consumption, feed conversion, growth rates, mortalities and proximate composition. It was found that diet impacts significantly on the growth and survival rates of this whelk, with bivalve feeds resulting in significantly higher consumption (P < 0.0001) and growth rates (P < 0.0001) compared to artificial pellets, despite similar feed conversion ratios (P = 0.359). The artificial pellets were found to have significantly less moisture, but higher protein, glycogen and lipid content than the bivalve feeds (P < 0.05) and resulted in whelk flesh with significantly higher energy and ash content (P < 0.05). D. orbita showed a preference for scavenging frozen bivalves over predation on live molluscs in captivity, which could reflect an optimal foraging strategy to minimise the energy required to subdue prey. Overall, juvenile D. orbita display similar growth (up to 0.8 g/month) and high survival (> 90%) compared to other gastropods in culture. Their flesh has a high calorific value (∼ 19 kJ/g), with significantly higher protein (> 26 mg/g) and glycogen (> 35 mg/g) content than their bivalve prey (P < 0.05). Consequently, this species has a promising future as a new species for molluscan aquaculture in Australia.
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Skye Heather Woodcock et al.A proposed functional role for indole derivatives in reproduction and defense of the Muricidae (Neogastropoda : Mollusca)http://epubs.scu.edu.au/merc_pubs/65
http://epubs.scu.edu.au/merc_pubs/65Tue, 26 Jun 2012 16:45:31 PDT
The Muricidae, also known as Murex or purple snails, are remarkable both as a source of the ancient indigoid dye, Tyrian purple and the homeopathic remedy "Murex", prescribed for the relief of women's problems. This purple secretion contains brominated indoles and indirubins with established antibiotic and anticancer properties, as well as choline esters with muscle relaxing activity. These properties have prompted considerable speculation, but little directed research, into the selective benefits of these bioactive compounds for the Muricidae. Consequently, this paper reviews the current literature on indole derivatives, their biosynthesis and associated bioactivities, with the aim of amassing evidence for a naturally selected function in the Muricidae.
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C B. Westley et al.